It’s not about easier or harder. Spammers don’t care how hard it is to put stupid moneys or dogs or whatever the fuck on chain. They don’t even care how much shit costs. Higher Expense just means rarity to their twisted little brains.
1. It’s not very hard to do this to begin with. block 273,536 contains a 14.4kb image of Nelson Mandela embedded across multiple transactions using pay to fake public keys. This has no limit.
2. Limiting op_return just pushes more bloat to the utxo and is objectively worse for the chain in the long run.
Bitcoin is a bad data storage system but it is designed is such a way that you can’t stop people from doing stupid shit. Making it possible to do stupid shit in a less harmful way seems better than making it only possible to do maximal harm regardless of your intentions. Wishing for people to be perfect angels is not how bitcoin operates.